A novel method to automatically detect and measure the ages of star clusters in nearby galaxies: Application to the Large Magellanic Cloud

TL;DR

This paper introduces a new automated method for detecting and dating star clusters in nearby galaxies, demonstrating its effectiveness through application to the Large Magellanic Cloud and revealing insights into its star formation history.

Contribution

A fully-automated statistical and Bayesian approach for star cluster detection and age estimation, outperforming previous methods especially in crowded fields.

Findings

Detected 4850 clusters in the LMC, including 3451 new ones.

Identified multiple star formation epochs, notably around 310 Myr ago.

Suggested an inside-out cluster formation pattern over the past billion years.

Abstract

We present our new, fully-automated method to detect and measure the ages of star clusters in nearby galaxies, where individual stars can be resolved. The method relies purely on statistical analysis of observations and Monte-Carlo simulations to define stellar overdensities in the data. It decontaminates the cluster color-magnitude diagrams and, using a revised version of the Bayesian isochrone fitting code of Ramirez-Siordia et al., estimates the ages of the clusters. Comparisons of our estimates with those from other surveys show the superiority of our method to extract and measure the ages of star clusters, even in the most crowded fields. An application of our method is shown for the high-resolution, multi-band imaging of the Large Magellanic Cloud. We detect 4850 clusters in the 7 deg2 we surveyed, 3451 of which have not been reported before. Our findings suggest multiple epochs of star cluster formation, with the most probable occurring ~310 Myr ago. Several of these events are consistent with the epochs of the interactions among the Large and Small Magellanic Clouds, and the Galaxy, as predicted by N-body numerical simulations. Finally, the spatially resolved star cluster formation history may suggest an inside-out cluster formation scenario throughout the LMC, for the past 1 Gyr.